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Senavirathna, Binura Madujith

University of British Columbia

Passive Gravity Driven Membrane Filtration (PGDMF) systems were specifically developed to ensure long-term access to safe drinking water in small, remote, and marginalized communities. Chemical cleaning protocols exist for conventional Ultrafiltration (UF) filtration systems to effectively remove physically irreversible foulants. The same protocols have been applied to PGDMF systems, but with limited success. Therefore, modified chemical cleaning protocols are needed for PGDMF systems. The present study systematically assessed the efficacy of different chemical cleaning protocols using sodium hypochlorite as the only chemical cleaning agent. The study utilized PVDF hollow fiber membranes harvested from the full-scale PGDMF system that provides drinking water to the Kleekhoot Reserve of the Hupacasath First Nation in British Columbia, Canada. Bench-scale chemical cleaning trials were carried out with a total of 162 chemical soak experiments (including duplicates) on harvested fibers, for different combinations of concentration of sodium hypochlorite, soaking temperature, and soaking (i.e., exposure) duration. The results indicated that the recovery in resistance due to fouling during chemical cleaning with sodium hypochlorite was governed by two rates: an initial rapid rate of recovery and a subsequent slow rate of recovery. Despite differing rates, both reactions exhibited a similar extent of recovery. It was concluded that effective recovery in the resistance due to fouling can be achieved using sodium hypochlorite as the only chemical cleaning agent. The required duration of chemical cleaning increases with higher targeted recoveries in resistance due to fouling and is also greater at lower temperatures and concentrations of sodium hypochlorite. An approach was proposed to establish chemical cleaning protocols based on site-specific conditions.

Text

2024-04-29

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88070

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/